Current Response Research Articles

A novel electrocatalyst based on NiO@C-dot nanocomposites for sensitive determination of ophthalmic drugs

This study proposed a novel electrochemical sensor for the sensitive measurement of the eye medication ofloxacin (OFX), which is based on a NiO@C-dot nanocomposite. The NiO@C-dot nanocomposite was synthesized using the sol-gel method, which was then applied to alter a glassy carbon electrode (GCE). With regard to OFX, the modified GCE shown outstanding electrochemical activity along with good sensitivity, selectivity, and stability. With OFX concentrations ranging from 5 µM to 975 µM, the NiO@C-dot/GCE showed a linear relationship with a sensitivity of 0.63994 µA/µM. The limit of detection (LOD) was 0.023 µM. The response to 50 µM OFX was measured, and the electrode was stored at 4°C after each test in order to evaluate the sensor's long-term stability and repeatability. After 20 days, the peak current response was still 97.89 % of its initial value. After 40 days of prolonged storage, 93.78 % of the electrode's original responsiveness was retained. The sensor showed a recovery rate of 97.37–99.70 % in all sample types when it was used to detect OFX in human urine, tap water, and food samples. These findings highlight the NiO@C-dot/GCE's outstanding selectivity, dependability, and longevity as solid platforms for OFX detection in complicated samples for a range of applications.

Fluorescence and electron transfer of Limnospira indica functionalized biophotoelectrodes

Cyanobacteria play a crucial role in global carbon and nitrogen cycles through photosynthesis, making them valuable subjects for understanding the factors influencing their light utilization efficiency. Photosynthetic microorganisms offer a promising avenue for sustainable energy conversion in the field of photovoltaics. It was demonstrated before that application of an external electric field to the microbial biofilm or cell improves electron transfer kinetics and, consequently, efficiency of power generation. We have integrated live cyanobacterial cultures into photovoltaic devices by embedding Limnospira indica PCC 8005 cyanobacteria in agar and PEDOT:PSS matrices on the surface of boron-doped diamond electrodes. We have subjected them to varying external polarizations while simultaneously measuring current response and photosynthetic performance. For the latter, we employed Pulse-Amplitude-Modulation (PAM) fluorometry as a non-invasive and real-time monitoring tool. Our study demonstrates an improved light utilization efficiency for L. indica PCC 8005 when immobilized in a conductive matrix, particularly so for low-intensity light. Simultaneously, the impact of electrical polarization as an environmental factor influencing the photosynthetic apparatus diminishes as matrix conductivity increases. This results in only a slight decrease in light utilization efficiency for the illuminated sample compared to the dark-adapted state.

Enhancing Prehospital Care During the Conflict in Ukraine: NATO's Role in Global Health Engagement.

The conflict in Ukraine, ongoing since 2014 and escalating with the Russian invasion in 2022, has unveiled profound challenges in prehospital care essential for the survival and recovery of warfighters and civilians alike, necessitating a detailed examination of the current medical response mechanisms and their effectiveness. This study provides an overview of these challenges and examines how these critical vulnerabilities have impacted the delivery of medical care in war-torn regions. It also explores the role of NATO and its member states in addressing these challenges, focusing on the efforts to standardize prehospital care, enhance training, and foster interoperability among medical services. Furthermore, it explores the role of global heath engagement through NGOs in addressing these prehospital care gaps within the Ukrainian conflict zone, drawing from direct observations, expert testimonials, and secondary data. Findings reveal significant enhancements in prehospital care through improved training, interoperability, and logistics management, despite ongoing challenges in medical infrastructure and extended evacuation times, which continue to impact the quality of care. The study underscores the critical role of international collaboration and standardized protocols in bolstering prehospital medical responses in conflict settings, highlighting the need for continuous adaptation and support to mitigate the complexities of modern warfare. The insights gained from the Ukraine conflict offer valuable lessons for future military and humanitarian medical responses in similar conflict settings.

Navigating dual hazards: Managing hurricane evacuation and sheltering operations Amidst COVID-19

Hurricane Laura made landfall in August of 2020 as a Category 4 storm, heavily affecting the coastlines of Texas and Louisiana. At the same time, both areas were coping with a surge in COVID-19 cases absent a vaccine. For this study, we explored how emergency management stakeholders navigated evacuation, sheltering, and re-entry planning and operations during a dual hazard threat where hurricane risk reduction measures contradicted COVID-19 risk reduction measures. We conducted 35 semi-structured interviews with emergency management stakeholders in Texas and Louisiana in the spring of 2021. Participants were recruited using a purposive sampling strategy designed to identify agency representatives and other officials involved with planning for hurricane season and with the Hurricane Laura response effort. We used thematic analysis to code and analyze the data. Findings suggest that while the process for planning for hurricanes had to shift to an online approach, the plan for addressing hurricane season was largely unchanged from the perspective of most participants until days before impact, when the decision was made to move to noncongregate sheltering. This led to adaptive and creative improvisation on the part of participants managing the evacuation and sheltering operations. Likewise, we found that caring for and communicating with evacuees in a noncongregate setting presented unanticipated challenges that required improvisation to address. Given the continued threat posed by COVID-19 and other respiratory illnesses, this study provides insights that emergency management stakeholders could apply to current and future planning and response efforts for hazards that require evacuation and sheltering.

How the COVID-19 pandemic reshaped telepsychology: Insights from an Italian survey

The coronavirus disease 2019 (COVID-19) pandemic rapidly boosted the introduction of certain changes in mental healthcare services, consequently driving up the adoption of remote care delivery options. We conducted an online Italian survey to evaluate telepsychology use, attitudes, acceptance, and training needs, as well as to understand patient-professional interactions in video-consultations, aiming to inform future mental healthcare practices and policies. The current study's survey responses were collected using an anonymous, self-reported questionnaire on the ‘REDCap’ platform from 25 October 2022 to 26 July 2023. In total, 128 mental health professionals and 113 patients completed the survey. In our sample, 69 % of patients and 79.7 % of mental health professionals reported having used telepsychology during COVID-19 pandemic; in particular, 84.6 % of patients and 95.1 % of professionals selected video-consultation modality. Data showed that participants expressed high satisfaction with this communication tool. The increase in satisfaction was directly proportional to increase in the quality of interactions and in relation to the quality of the experiences. The critical factors influencing the video-consultation experience include communication style, information completeness, patient-centredness, and the comfort underscoring the central role of the professional-patient relationship, which, substantially, remains a key element in the psychological treatment process. These findings reinforce the need for continued refinement and expansion of telepsychology services, thus highlighting the potential for integrating innovative technologies into mental health practise.

An ultrasensitive electrochemical biosensor with dual-amplification mode and enzyme-deposited silver for detection of miR-205-5p.

An electrochemical biosensor based on dual-amplified nucleic acid mode and biocatalytic silver deposition was constructed using catalytic hairpin assembly-hybrid chain reaction (CHA-HCR). The electrochemical detection of silver on the electrode by linear sweep voltammetry (LSV) can be utilized to quantitatively measure miR-205-5p since the amount of silver deposited on the electrode is proportional to the target nucleic acid. The current response values exhibit strong linearity with the logarithm of miR-205-5p concentrations ranging from 0.1pM to 10μM, and the detection limit is 28 fM. A consistent trend was found in the results of the qRT-PCR and electrochemical biosensor techniques, which were employed to determine the total RNA recovered from cells, respectively. Moreover, the constructed sensor was used to assess miR-205-5p on various cell counts, and the outcomes demonstrated the excellent analytical efficiency of the proposed strategy. Therecoveries ranged from 97.85% to 115.3% with RSDs of 2.251% to 4.869% in human serum samples. Our electrochemical biosensor for miR-205-5p detection exhibits good specificity, high sensitivity, repeatability, and stability. It is a potentially useful sensing platform for tumor diagnosis and tumortype identificationin clinical settings.

Physical Reservoir Computing Using van der Waals Ferroelectrics for Acoustic Keyword Spotting.

Acoustic keyword spotting (KWS) plays a pivotal role in the voice-activated systems of artificial intelligence (AI), allowing for hands-free interactions between humans and smart devices through information retrieval of the voice commands. The cloud computing technology integrated with the artificial neural networks has been employed to execute the KWS tasks, which however suffers from propagation delay and the risk of privacy breach. Here, we report a single-node reservoir computing (RC) system based on the CuInP2S6 (CIPS)/graphene heterostructure planar device for implementing the KWS task with low computation cost. Through deliberately tuning the Schottky barrier height at the ferroelectric CIPS interfaces for the thermionic injection and transport of the electrons, the typical nonlinear current response and fading memory characteristics are achieved in the device. Additionally, the device exhibits diverse synaptic plasticity with an excellent separation capability of the temporal information. We construct a RC system through employing the ferroelectric device as the physical node to spot the acoustic keywords, i.e., the natural numbers from 1 to 9 based on simulation, in which the system demonstrates outstanding performance with high accuracy rate (>94.6%) and recall rate (>92.0%). Our work promises physical RC in single-node configuration as a prospective computing platform to process the acoustic keywords, promoting its applications in the artificial auditory system at the edge.

Perovskite versus Standard Photodetectors.

Perovskites have been largely implemented into optoelectronics as they provide several advantages such as long carrier diffusion length, high absorption coefficient, high carrier mobility, shallow defect levels and finally, high crystal quality. The brisk technological development of perovskite devices is connected to their relative simplicity, high-efficiency processing and low production cost. Significant improvement has been made in the detection performance and the photodetectors' design, especially operating in the visible (VIS) and near-infrared (NIR) regions. This paper attempts to determine the importance of those devices in the broad group of standard VIS and NIR detectors. The paper evaluates the most important parameters of perovskite detectors, including current responsivity (R), detectivity (D*) and response time (τ), compared to the standard photodiodes (PDs) available on the commercial market. The conclusions presented in this work are based on an analysis of the reported data in the vast pieces of literature. A large discrepancy is observed in the demonstrated R and D*, which may be due to two reasons: immature device technology and erroneous D* estimates. The published performance at room temperature is even higher than that reported for typical detectors. The utmost D* for perovskite detectors is three to four orders of magnitude higher than commercially available VIS PDs. Some papers report a D* close to the physical limit defined by signal fluctuations and background radiation. However, it is likely that this performance is overestimated. Finally, the paper concludes with an attempt to determine the progress of perovskite optoelectronic devices in the future.

First approach of fractals nickel-copper dendrites on stainless steel electrodes for ammonia oxidation to nitrogen monitored in operando by differential electrochemical mass spectroscopy

Fractal nickel-copper dendrites were synthesized by electrochemical deposition (ECD) on a stainless steel electrode (SS/NiCu). The electrode surface was characterized using Field Emission Scanning Electron Microscopy (FE-SEM), X-ray diffractometry (XRD), and Raman spectroscopy. The Ni-Cu molar ratio and the time applied in the ECD method were studied, revealing that both are critical factors in modifying and controlling the surface morphology. The SS/NiCu electrodes show a higher density current response when exposed to ammonium hydroxide, reaching a limiting current density at concentrations above 0.050 M NH4OH. Ammonia oxidation reaction (AOR) was monitored in operando using differential electrochemical mass spectroscopy (DEMS). When a bias potential over +1.50 V (vs. RHE) was applied, the evolution of oxygen and NO was observed. However, N2 was the only oxidation product at a constant potential below +1.50 V (vs. RHE). Oxygen (O2) evolution was the main competitive reaction during the AOR. The results show that products are strongly dependent on the electrochemical perturbation applied. The study demonstrated that the SS/NiCu electrodes are suitable for AOR to N2 in high alkaline conditions.

Electrochemical detection of FTO with N3-kethoxal labeling and MazF cleavage.

N6-Methyladenosine (m6A) is a prevalent modification in eukaryotic mRNAs and is linked to various human cancers. The fat mass and obesity-associated protein (FTO), a key m6A demethylase, is crucial in m6A regulation, affecting many biological processes and diseases. Detecting FTO is vital for clinical and research applications. Our study leverages the specific cleavage properties of the MazF endoribonuclease to design an electrochemical method with signal amplification guided by streptavidin-horseradish peroxidase (SA-HRP), intended for FTO detection. Initially, the compound N3-kethoxal is employed for its reversible tagging ability, selectively attaching to guanine (G) bases. Subsequently, dibenzocyclooctyne polyethylene glycol biotin (DBCO-PEG4-Biotin), is introduced through a reaction with N3-kethoxal. HRP is then employed to catalyze the redox system to enhance the current response further. A promising linear correlation between the peak current and the FTO concentration was observed within the range of 7.90 × 10-8 to 3.50 × 10-7 M, with a detection limit of 5.80 × 10-8 M. Moreover, this method assessed the FTO inhibitor FB23's inhibitory effect, revealing a final IC50 value of 54.73 nM. This result aligns with the IC50 value of 60 nM obtained through alternative methods and is very close to the values reported in the literature. The study provides reference value for research into obesity, diabetes, cancer, and other FTO-related diseases, as well as for the screening of potential therapeutic drugs.

Youth justice-involved LGBTIQA+ young people: exploring practitioner and policy perspectives

ABSTRACT A growing body of research explores the intersectional needs and experiences of youth justice (YJ)-involved young people. However, there remains limited research on the experiences of and service responses to justice-involved lesbian, gay, bisexual, transgender, intersex, queer, asexual and other sexually or gender-diverse (LGBTIQA+) young people. This paper contributes practitioner and policy perspectives on the topic, with focus group data from one Australian jurisdiction and a review of jurisdictional YJ policy directions. In relation to LGBTIQA+ young people, the study found that: intersectional factors influence experiences of and engagement with services; pathways to justice-system contact are variable and influenced by several factors; current service responses have several limitations in both statutory and non-statutory settings; young people’s experiences in one service influence their experiences and engagement with other services. These findings are largely unreflected in current state and territory YJ policy direction documents. The findings can inform policy and practice with justice-involved LGBTIQA+ young people in Australia and provide recommendations for future research. IMPLICATIONS: Current limitations to practice with justice-involved LGBTIQA+ young people cannot be addressed fully by individual practitioners or organisations. Identified practice concerns and limitations are largely not reflected in current state and territory YJ policy direction. Further research should explore perspectives of justice-involved LGBTIQA+ young people.

Lactate threshold evaluation in swimming using a sweat lactate sensor: A prospective study.

Since assessing aerobic capacity is key to enhancing swimming performance, a simple and widely applicable technology should be developed. Therefore, we aimed to noninvasively visualize real-time changes in sweat lactate (sLA) levels during swimming and investigate the relationship between lactate thresholds in sweat (sLT) and blood (bLT). This prospective study included 24 university swimmers (age: 20.7s±1.8years, 58% male) who underwent exercise tests at incremental speeds with or without breaks in a swimming flume to measure heart rate (HR), bLT, and sLT based on sLA levels using a waterproof wearable lactate sensor attached to the dorsal upper arm on two different days. The correlation coefficient and Bland-Altman methods were used to verify the similarities of the sLT with bLT and personal performance. In all tests, dynamic changes in sLA levels were continuously measured and projected onto the wearable device without delay, artifacts, or contamination. Following an initial minimal current response, with increasing speed the sLA levels increased substantially, coinciding with a continuous rise in HR. The speed at sLT strongly correlated with that at bLT (p<0.01 and r=0.824). The Bland-Altman plot showed a strong agreement (mean difference: 0.08±0.1m/s). This prospective study achieved real-time sLA monitoring during swimming, even with vigorous movement. The sLT closely approximated bLT; both were subsequently validated for their relevance to performance.

A Novel Electrochemical Method to Detect HIV in Saliva

Human Immunodeficiency Virus (HIV) is a global epidemic that causes acquired immunodeficiency syndrome (AIDS) with time. Approximately 14% (one in seven) of HIV-infected people do not know their HIV status till 2022 [1]. These people have a higher chance of spreading HIV without knowing its consequences. So, there is an unmet need for more HIV testing techniques to isolate and identify all HIV-infected people as soon as after their infection. Till now, there are no available techniques to detect HIV in saliva due to HIV’s low concentrations and the inhibition properties of saliva. We developed a nickel-based electrochemical method to detect HIV in saliva for the first time. This method does not require any biorecognition element for the detection, thus making it label-free. The difference in current responses during the chronoamperometry helps to distinguish HIV from saliva. It happens due to the blocking of the formation of NiOOH in the presence of HIV on the nickel surface. This method has high sensitivity and exhibits a linear current trend with increasing concentrations of HIV culture fluid. Also, it has a lower detection limit of around 50 copies/mL and a high selectivity of HIV over Epstein-Barr Virus (EBV), which is the most common co-infection for HIV patients. Also, the most common route to transmit EBV is through saliva. So, this novel method will create a new opportunity for the commercialization of non-invasive HIV testing techniques that minimize the spreading rate of HIV by fastening HIV testing.[1] “Global HIV & AIDS statistics — Fact sheet.” Accessed: Nov. 26, 2023. [Online]. Available: https://www.unaids.org/en/resources/fact-sheet

Redox Stability Analysis of Co-Doped Barium Niobate Thin Films Via Cyclic Voltammetry

The electrochemical oxidative coupling of methane (E-OCM) to higher hydrocarbons, requires anodes that are stable under reducing conditions. We have previously demonstrated high activity with long term stability/durability for the perovskite anode BaMg0.33Nb0.67-xFexO3-δ (BMNF) while performing E-OCM1. Our group has also improved the total conductivity and activity of barium niobate perovskites via exchange of Mg for Ca (from 18 mS/cm-1 to 41 mS/cm-1), while also decreasing the Goldschmidt tolerance factor below 1 for increased cubic perovskite structural stability2. Perovskite metal oxide thin films can be produced with well-defined thicknesses and stoichiometries through pulsed laser deposition (PLD)3. These thin films are utilized in cyclic voltammetry experiments on YSZ substrates to further elucidate the chemical stability and oxygen sub-stoichiometry of high temperature SOFC/SOEC electrodes. Through application of reducing potentials to the electrode of interest, the voltage and current responses can be correlated to effective oxygen activities in which reduction of the electrode may occur. Usage of this technique with calcium and iron doped barium niobate perovskites (BaCa0.33Nb0.67-xFexO3-δ - BCNF) provides insights into the thermochemical stability and iron doping effects under highly reducing environments. The BCNF thin film electrodes were characterized via grazing incidence XRD and XRF for crystal structure and chemical composition. After initial characterization, cyclic voltammetry experiments were performed in a novel cell setup. These BCNF thin films show promise for evaluating stability mechanisms for E-OCM operation while providing details on compositional changes and oxygen loss of BCNF in reducing environments.

Upcycling Compact Disks to Flexible Nanoporous Gold Electrodes for Nitrite Biosensing

Electrochemical biosensors are crucial in disease detection due to their simplicity, rapidity, and sensitivity. As a wearable or e-skin platform, electrochemical sensors are frequently restricted by gradual degradation, complexity, limited active surface area, arduous fabrication process, and high cost. Therefore, soft electrochemical biosensors that are mechanically biocompatible, easy to prototype, and robust for sensitive biosensing are highly sought. To mitigate such an issue, recordable compact disks (CDs) have been upcycled to advanced biosensors exhibiting flexible and disposable and being applicable to various biomedical applications, making them an economical and practical option. However, the limited surface area of the gold CDs electrode prevents optimal electrochemical catalytic performance. Nanostructure has been widely embedded in electrochemical biosensor construction to optimize electrode surface area and the number of active sites, which can contribute to improved detection sensitivity, selectivity, and electron transfer.Here, we aim to develop an advanced nanoporous gold film electrode (NPGFE) from CD for a simple, flexible, sensitive, and larger surface area electrode with reproducible areas. The fabrication and modification of gold CDs film were accomplished through two steps: 1) A mechanical cutter tailored the gold film after being transferred from CDs into a flexible substrate (Polyimide tape). Before placing the CDs film between the two laminating sheets, an aperture (1 mm diameter) was made in one of the laminating sheets to expose the tailored gold film electrode (GFE) and insulate the undesired area using a thermal laminator to ensure an adequate seal as a simple and low-cost approach; 2) The nanoporous gold (NPG) was electrochemically deposited onto the gold CDs film surface in gold (III) chloride trihydrate (HAuCl4·3H2O) and ammonium chloride (NH4Cl) solution at a potential of -4V for 100 s. Surface morphology characteristics and elemental analyses were investigated using scanning electron microscopy, while electrochemical studies were carried out in the CH Instruments potentiostat.The SEM images confirm a homogeneous distribution of NPG across the electrode’s surface. The energy-dispersive X-ray analyses exhibited the purity of the deposited NPG. The effective surface area was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in 1 M KCl and 1 mM K3[Fe(CN)6] solution. From the slope of the Ip vs. v1/2 plot and the Randles-Sevcik equation, the active surface area of the NPGFE was significantly increased compared to the unmodified GFE. EIS was conducted to evaluate electron transfer resistance and obtain the semicircular diameter in Nyquist plots. In comparison to the unmodified GFE, the NPGFE showed a semicircle with a smaller diameter, indicating that the electron transfer resistance is minimized. The electrochemical characterization of the NPGFE was investigated by CV and amperometric techniques in 0.1 M PBS solution at ambient temperature (25°C) and pH 7.4. The NPGFE performance was studied at a fixed potential (0.77 V vs. Ag/AgCl) by analyzing the current response upon adding nitrite and anodic peak current at a potential range from 0.3 to 0.9 V (vs. Ag/AgCl). The calibration curve plot was linear over 0.5 μM to 9 mM with 20 nA·μM−1·cm−2 sensitivity and a low detection limit of 0.5 μM with a correlation coefficient (R2) of 0.99. The NPGFE's reproducibility reusability studies were conducted to evaluate electrode stability when prepared independently and utilized repeatedly under the same condition. Results demonstrate remarkable reproducibility and highly satisfactory reusability, making it suitable for practical application. The effect of pH on nitrite detection was investigated at different pH values. The anodic peak currents decreased and shifted to the low potential when the pH was increased from 5.0 to 10.0, indicating that protons were directly involved in the nitrite redox reaction. Also, the selectivity studies showed a significant increase in the current response when nitrite, ascorbic acid, and sodium sulfite were introduced to the solution, and there were no remarkable changes when other interferents were added. The long-term stability results showed that the NPGFE retains 99% of its initial current response to NO2 - after six months of storage, indicating satisfactory stability and long service life of NPGFE. Importantly, the sensing performance while stretching the NPGFE will be investigated to produce biocompatible relevant results.The flexible, nanoporous upcycled CDs electrode utilizing craft machines provide fast prototyping electrochemical biosensors for skin-interfaced bioelectronics. The nanoporous CD-based biosensor significantly improves electrocatalytic performance toward nitrite detection along with exceptional improvements in the cost-effective and sustainable fabrication process for flexible electronics. Future work relies on developing system-integrated biosensors based on systematic reliability and feasibility tests. Soft upcycled bioelectronics holds significant potential in advancing biomedical in situ real-time analysis in various platforms of flexible and nanostructured biosensors. Figure 1

A Novel Cerium Oxide/Gold/Carbon Nanocomposite-Based Electrochemical Sensor for Detecting Hydroxyl Radicals

Hydroxyl radicals (•OH), a type of reactive oxygen species (ROS), play a crucial role in maintaining the normal physiological processes of human cells. Nevertheless, an excessive accumulation of these radicals may perturb cellular mechanisms, so triggering the onset of severe diseases, including cancer, neurological disorders, and heart disease. The detection of •OH is thus of utmost importance in the early diagnosis of these disorders. The combination of an electrochemical methodology with a recognition system is considered as a promising approach for the detection of •OH. This is primarily due to its capacity to provide fast and direct readings without the need for any preliminary sample preparation. This study presents the development of a new electrochemical sensor for the detection of •OH. The sensor was developed by modifying a screen-printed carbon electrode (SPCE) with a nanocomposite consisting of cerium oxide nanoclusters (CeOx), gold nanoparticles (AuNPs), and a highly conductive carbon. The synthesis of AuNPs supported by carbon was carried out using a deposition-precipitation process. Subsequently, the meticulous deposition of CeOx nanoclusters onto the AuNPs was achieved by the use of surface organometallic chemistry (SOMC). Energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM) were applied to assess the distribution of AuNPs on the carbon substrate and their subsequent embellishment with CeOx nanoclusters. The actual loadings of Ce and Au present in the nanocomposite were measured using inductively coupled plasma optical emission spectroscopy (ICP-OES). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed to analyze the electrochemical responses resulting from the interaction of the CeOx-Au/Carbon nanocomposite with •OH. The CV results demonstrated that the proposed sensor exhibited the capability to effectively identify the presence of •OH in the Fenton reaction, with a notably low limit of detection of 58 µM. The sensor demonstrated a linear correlation between the current response and the concentration of •OH, within the range of 0.05 to 5 mM. Compared to a sensor modified with CeOx/Carbon, the CeOx-Au/Carbon-modified sensor exhibited enhanced electrochemical performance, as demonstrated by an increased current response and a reduced peak potential difference when detecting •OH radicals. Furthermore, the EIS studies showed that the sensor could distinguish •OH from other comparable ROS, such as hydrogen peroxide (H2O2).

(Invited) Wearable Pocket-Sized Fully Non-Contact Cardiorespiratory Sensor

Cardiovascular and respiratory diseases have emerged as the leading cause of global mortality over the past decade, encompassing conditions such as atrial fibrillation and chronic obstructive pulmonary disease. Consequently, continuous monitoring plays a crucial role in managing these conditions, as it enables early detection, improves patient survival rates, and alleviates the burden on emergency medical resources. Our research group has developed a wearable pocket-sized fully non-contact cardiorespiratory sensor that utilizes electromagnetic induction technology to measure dynamic changes in electrical conductivity resulting from cardiac contractions and pulmonary volume variations. This enables the continuous acquisition of eddy current damping response signals to achieve cardiorespiratory monitoring. In comparison to commercially available ECGs, PPG smartwatches, and respiratory sensors, our proposed pocket-sized sensor offers three major advantages: exceptional concealment, convenience, and comfort for health monitoring due to its pocket-sized and micro-structured design; simultaneous acquisition of two-dimensional cardiac and respiratory signals, facilitating comprehensive cardiorespiratory health monitoring; and the ability to adjust sensing depth through frequency modulation of the electromagnetic field, thus eliminating variations in physiological structures among subjects and achieving optimized sensing and personalized medical benefits.

Stability of Bipolar Plates in Proton Exchange Membrane Water Electrolysis: Dissolution Studies of Titanium and Stainless Steel

Due to its high current densities and fast system response proton exchange membrane water electrolysis (PEMWE) is an ideal system for green hydrogen production from renewable energies. However, its widespread use is still hindered by the high costs rendering the produced green hydrogen not competitive. Therefore, a cost reduction is highly needed. The bipolar plates (BPPs) are causing a colossal factor in material costs. They are usually produced from titanium and coated with even more expensive materials such as gold or platinum. A possible, cheaper alternative is stainless steel. However, it is suspected to suffer from corrosion leading to the leaching of cations that can poison the catalyst or membrane.[1] Thus, we investigated the stability of BPP materials, the currently used titanium, and its cheaper alternative stainless steel (316L).[2] Therefore, we use a modified scanning flow cell setup coupled to an inductively coupled plasma mass spectrometer for investigating the stability of both materials on-line, as well as with scanning electron microscopy. To mimic the conditions at the BPP under operation, deionized (DI) water and highly diluted (0.5 mM) H2SO4 are chosen as electrolytes combined with a sample temperature of 60 °C.For Ti, we show that the dissolution is negligible, whereas 316L corrodes. For 316L, in DI water mainly Cr dissolves, while in the H2SO4 solution, the dissolution is more pronounced, and all alloy components are detected. Besides the pH value, the applied potentials play a crucial for its stability. However, our findings suggest that the contamination for a typical full cell architecture remains below 1 ppm, even for the highest measured dissolution rate of SS 316L.These capabilities of on-line high-throughput stability tests for BPP materials are, furthermore, used to investigate the influence of contaminations, such as F- or Cl-, and of the temperature-dependence on the stability of 316L. These results give further insights into 316L stability as BPP material and therefore contribute to the development towards cost-effective PEMWE.[1] a) N. Rojas, M. Sánchez-Molina, G. Sevilla, E. Amores, E. Almandoz, J. Esparza, M. R. Cruz Vivas, C. Colominas, Int. J. Hydrogen Energy 2021, 46, 25929-25943; b) H. Becker, J. Murawski, D. V. Shinde, I. E. L. Stephens, G. Hinds, G. Smith, Sustain. Energy Fuels 2023, 7, 1565-1603.[2] L. Fiedler, T. C. Ma, B. Fritsch, J. H. Risse, M. Lechner, D. Dworschak, M. Merklein, K. J. J. Mayrhofer, A. Hutzler, ChemElectroChem 2023, e202300373. Figure 1

The Heterogeneity of Turn-over Number in Electrocatalysis

Chemical catalysts dominate the multi-billion global revenue of the chemical industry because they accelerate the time it takes a particular reaction to reach equilibrium without altering the equilibrium constant. Electrocatalysis can provide significant benefits compared to other methods, as it has minimal purification and separation costs, is operational at low temperatures and pressures, replaces hazardous and toxic chemical sources with electric current, and can be integrated with renewable energy sources. From a techno-economical point of view, some considerations are critical during a catalyst design: cost, activity, and durability. One useful metric to quantify catalyst durability is turn-over number (TON), which represents the maximum yield of products attainable from a catalytic center. Mathematically speaking, the TON is defined as: TON = ∫0 ∞ TOF(t) dt, where TOF is the turn-over frequency, which is the rate of turn-overs (N) per active site. Currently, without any exception, the TON is given as a fixed number describing the total amount of substrate converted until the catalysts fully degrade. Our approach studies electrocatalytic deactivation processes at the single catalyst level using a technique entitled single-entity electrochemistry for freely diffusing catalysts. The hydrogen evolution reaction (HER) is investigated with platinum nanoparticles as the model catalyst because it deactivates at the nanoscale when the catalytic activity decreases over time. At specific applied potentials, the current measured when a single platinum nanoparticle impacts the electrode creates a transient spike and decay back to the baseline current. TON is quantified by fitting the current decay response and integrating above the fit to find the charge transferred to catalyze the reaction. Our results show that electrocatalyst degradation and TON have a distribution, where some catalysts are more stable than others, and depends on the applied potential and size of the nanoparticles. In order to study how the surface facets of platinum affect the TON, SECCM was coupled with scanning electron microscopy (SEM) to compare the deactivation of a polycrystalline platinum surface in the macro scale with immobilized platinum nanoparticles on a glassy carbon surface. Combining local structural, electrochemical activity, and durability will bridge our fundamental understanding of macro and nanoscale catalyst deactivation processes to assist in the bottom-up approach of material development and design of large-scale industrial electrocatalysts.

The Development of a Versatile Activation Protocol for Carbon-Infused Thermoplastic-Based 3D Printed Electrochemical Sensors

Point-of-care (POC) diagnostics is rapidly expanding as researchers continually develop advanced sensors and integrated devices with the goal of streamlining on-site detection and analysis. Recently, the utilization of 3D printing for rapid fabrication of housings, electrodes, and sensors for use at the POC has been realized and exploited towards diverse applications. Particularly interesting is the use of 3D printed carbon electrodes (3DpCEs) in POC diagnostics owing to its simplicity, affordability, and mass production capabilities for developing selective and sensitive sensors either for direct use or through post-printing surface modifications. Herein, a comprehensive investigation of an alkaline-assisted electrochemical activation (AAEA) protocol for the fabrication of sensitive and selective 3DpCEs was completed. In this study we explored the influence and effect of basicity, activation cycles, activation time, and scan rate. Following the optimization of the activated 3DpCEs, a comparative study was performed using nonactivated and alkaline immersed 3DpCEs, where AAEA 3DpCEs demonstrated higher current responses, improved reversibility, and significantly increased reproducibility. The AAEA protocol for 3DpCEs also provides a versatile modification protocol for the design of sensors capable of selectively detecting biomolecules in the presence of potential interferents. Using the developed protocol, the AAEA 3DpCEs were applied toward i) the selective separation and sensing of catechol and hydroquinone and ii) the detection of glucose using copper deposited 3DpCEs.